The 2007 revised mathematics curriculum in Ghana introduced many changes to the way mathematics should be taught and learned. However, before this research started in 2010, very little was known about how this subject is taught and learned. This study aims to investigate mathematics teachers’ teaching practices and students’ learning experiences in junior high schools (12-14 years) using a mixed methods design. The study’s conceptual framework is informed by two different, but interrelated theories: behaviourism and constructivism. Participants in the study were 24 mathematics teachers and 358 students from 12 schools. Semistructured questionnaires were used to collect quantitative data about participants’ perceptions, and classroom observations and interviews were used to collect qualitative data about actual classroom practices. The quantitative data was analysed using SPSS, STATSDIRECT and ORIGIN software and the qualitative data assessed using a thematic analysis approach. The key findings include: teachers and students espoused the belief that their teaching and learning practices are consistent with the principles and guidelines of the new mathematics curriculum. Teachers perceived teaching practices were complex as they contain both behaviourist and constructivist beliefs; however, their actual teaching practices were didactic. It also emerged that both teachers and students try to avoid making mistakes, despite the importance of correcting students’ misconceptions when promoting effective teaching and learning. The fact that peer influence is a key factor that shapes students’ learning was an important theme that emerged from the interview and the classroom observations. Students were only willing to participate in class discussions if they knew the correct answer, as they would be ridiculed by their peers for giving a wrong answer. The movement towards a more constructivist approach to teaching and learning, which is the prime objective of the new mathematics curriculum, occurred at a slower pace. Thus, a conceptual model for the teaching and learning of mathematics which advocates collaboration and partnership between teachers and students in the classroom is offered.